In recent years, with a rapid increase in the size of data being processed in information processing systems, a technique known as “storage virtualization” has been utilized for accommodating the increased data size.
The storage virtualization is a technique that enables multiple storage apparatuses to be virtually unified to form a large-capacity storage pool. The storage virtualization provides flexible configurations of storage pools in accordance with the business situations, by allocating areas necessary for the business from the storage pool, or by freeing up any areas that are not required anymore. Inputs and outputs (I/Os) are distributed across a virtual storage apparatus, which prevents any delays due to a heavy I/O loads converged on a particular storage apparatus.
Apparatuses which realize such storage virtualization are known as “storage virtualization apparatuses”. Storage apparatuses having storage pools which are embodied by such storage virtualization apparatuses are known as “virtual storage apparatuses”.
FIG. 16 is a schematic diagram illustrating a configuration of a conventional virtual storage apparatus 103.
The virtual storage apparatus 103 includes a storage virtualization apparatus 108 and a disk array apparatus 105. The disk array apparatus 105 includes control modules (CMs) 104-1 and 104-2 (CM #0 and CM #1) and multiple redundant array of independent disks (RAIDs) 401-403 (RAID #0-#2).
The storage virtualization apparatus 108 and the RAIDs 401-403 are connected via the CMs 104-1 and 104-2.
The storage virtualization apparatus 108 configures one or more storage pools 106 (storage pool #0) from physical volumes (not illustrated) created in the multiple RAIDs 401-403, and reserves a certain capacity from these storage pools 106 and provides a higher-level host apparatus with it as a virtual volume.
As used herein, the term “physical volume” refers to any storage area provided by the disk array apparatuses 4-1 to 4-m, and corresponds to a logical unit (LUN). Physical volumes are actually logical volumes, and are not the physical disk apparatuses, such as hard disk drives (HDDs) or solid state drives (SSDs); hereinafter, such physical volumes are collectively referred to as “physical disks”, and physically retain data in the RAIDs 401-403. For the sake of clarity, they are referred to as “physical volumes” herein in order to differentiate them from virtual volumes (described later) which are logical volumes.
The RAIDs 401-403 include physical disks, such as HDDs and/or SSDs, which provide storage areas for data. Furthermore, one or more physical volumes are created (defined) in the respective RAIDs 401-403.
In the virtual storage apparatus 103 as described above, in general, in order to improve the performance and/or distribute loads, configurations called “striping” have been widely adopted, wherein storage areas are reserved from the physical disks and are presented to a host apparatus and the like, as a single virtual volume.
In the virtual storage apparatus 103, physical disks in a wide variety of storage types (e.g., vendors, models, disk types) are used in physical volumes included in the storage pools 106. When a stripe is configured in the virtual storage apparatus 103, the performance of the resulting virtual volume is limited to the performance of the slowest physical volume.
As an example, one storage pool 106 is configured from physical volumes in the multiple RAIDs 401-403 having different RAID levels, such as from RAID 401 of RAID 5 (of which access speed is lower) and RAIDs 402 and 403 of RAID 1+0 (of which access speeds are higher). In this case, RAID 401 of RAID 5 which has an access speed slower compared to that of RAID 1+0 lowers the entire performance of the storage pools 106.
Such a performance difference is also caused by other differences, such as differences in disk type (e.g., HDDs or SSDs), or spin speeds of HDDs.
Furthermore, even if there is no difference in the performances of the physical volumes in the RAIDs 401-403, a system administrator may erroneously generate an unintended deterioration in the performance by making an error when a storage pools 106 is created manually.
Thus, in a virtual storage apparatus having a storage pool configured from physical volumes, it is desirable to enable a creation of a storage pool in a simplified manner without requiring any knowledge of the performances and/or characteristics of the physical volumes.